A series of conventional gloves made of synthetic materials including nitrile butadiene rubber (NBR), polyvinyl chloride (PVC), polyurethane (PU), polyethylene (PE), polychloroprene (CR), etc. had been used to substitute natural rubber latex gloves. The NBR glove is the most popular one among those conventional synthetic gloves.
U.S. Pat. No. 5,014,362 and Reissue U.S. Pat. No. Re. 35,616 invented by Tillotson et al. disclosed a glove comprising elastomeric material of nitrile butadiene rubber, characterized by: being substantially impermeable to water vapor and liquid water, and having a tensile strength of at least about 1500 psi as measured according to ASTM D-412 on a sample of the elastomeric material having a thickness of about 4.0 to 4.5 mils. Reviewing the specification of Tillotson's U.S. Pat. No. Re. 35,616, Table 2, the thickness of 4.5 mils (0.1143 mm) corresponds to a tensile strength of 2200 psi (according to ASTM D412). There is no disclosure in Tillotson's prior art about the relationship between the glove thickness and the abrasion or wear resistance of the glove.
Conventional methods to increase the abrasion resistance of the gloves, especially for medical or surgical uses, include: the adhesion of fibrous material to a thin-layer sheet material of the glove; the lamination of plural protective layers; or modification of glove formulation to increase the thickness for resisting abrasion or wear. However, the conventional methods to increase the glove thickness may result in reduction of its tensile strength or may affect the donning property when wearing the glove during use or in contact with poisonous, dangerous pollutants or contaminants in a hospital.
The present inventor has found these phenomena and invented the present modified NBR glove with increased thickness but without reducing its tensile strength.